Considering a coexistence of satellite and terrestrial networks, current investigations show that either the secure transmission of satellite communication or terrestrial communication is considered. To guarantee secure satellite communications, the signal-to-interference-plus-noise (SINR) of Eve for wiretapping satellite signals is decreased by terrestrial BS's cooperative BF, and the SINR of legitimate satellite user is increased[1]}, where the quality of service (QoS) of terrestrial link is guaranteed. The BS provides interference resource to assist secure satellite link in cognitive satellite-terrestrial communications[2]}. A secrecy-energy efficiency is considered while constrains the cellular users' rate requirements in a cognitive satellite-terrestrial network[3]}.
In addition, by exploiting the BS and a cooperative terminal as green interference resources, the Eve within the signal beampattern region of BS is degraded, where the interference level of satellite link is constrained[4]}. However, the work considering secure transmissions of both satellite and terrestrial communications has not been investigated, which motivates we conduct an investigation on physical layer security in integrated satellite-terrestrial communications.
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